Use of a spin trap in a cosmetic or dermatological composition

ABSTRACT

The invention relates to the use of a spin trap employed as an electron paramagnetic resonance measurement probe, in a cosmetic or dermatological composition for the light-protective, anti-ageing and/or anti-acne treatment of the skin. In particular, this spin trap is encapsulated in lipid vesicles which are capable of diffusing into the deep layers of the skin.

This is a Division of application Ser. No. 08/366,748 filed on Dec. 30,1994, now U.S. Pat. No. 5,569,663.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the use of a spin trap in a cosmeticand/or dermatological composition, for the light-protective, anti-ageingand/or anti-acne treatment of the skin, including the scalp. Theinvention also relates to a process for the topical cosmetic treatmentof the skin and to a cosmetic and/or dermatological compositioncontaining this spin trap.

2. Discussion of the Background

In order to provide an effective protection for the skin againstsunlight, to reduce the effects of age and to eliminate theimperfections of the skin caused by ache, it is currently necessary touse several antioxidant active agents; at present, effective care of theskin against these effects and imperfections is obtained byincorporating 4 to 8 antioxidant active agents. However, theintroduction of a large number of active agents into a cosmetic and/ordermatological composition complicates its manufacture, resultingparticularly in an increase in the cost price thereof.

Consequently, the subject of the invention is a cosmetic and/ordermatological composition and the use thereof for the light-protective,anti-ageing and/or anti-ache treatment of the skin which enables thesedrawbacks to be overcome.

Spin traps and more especially nitroxide free radicals are generallyused in spectroscopy as a probe for electron paramagnetic resonance(EPR), as described in the document "Electron paramagnetic resonance(EPR) imaging in skin: Biophysical and biochemical microscopy" by J.Fuchs et al., vol. 98, No. 5, 1992 p. 713 to 719 or U.S. Pat. No.4,849,346. The measuring is based on the reduction of the spin traps.

Nitroxide free radicals are also used for displaying human organs bymagnetic resonance study. More precisely, the subject of the inventionis a use for the light-protective, anti-ageing and/or anti-acnetreatment of the skin, of a spin trap employed as an electronparamagnetic resonance measurement probe, in a cosmetic ordermatological composition.

It has already been envisaged to inject a solution ofN-tert-butyl-α-phenylnitrone into rodents for the purpose of loweringthe level of oxidized proteins and of increasing the activity ofglutamine synthetase and of neutral protease in their brains: see inthis respect the document "Reversal of age-related increase in enzymeactivity, and loss in temporal and spatial memory by chronicadministration of the spin-trapping compoundN-tert-butyl-α-phenylnitrone" by J. M. Carney et al., Proc. Natl. Acad.Sci. vol. 88, pp. 3633-3636, May 1991; however, this document does notin any way contemplate the use of this nitrone in a cosmetic and/ordermatological composition for an anti-ageing, anti-acne and/orlight-protective treatment of the skin.

Moreover, it is known from document EP-A-0,327,263 to apply acomposition containing a free-radical precursor and an adjuvant such asa reducing agent, an antioxidant or a hydroxyl-radical-sequesteringagent to the scalp in order to stimulate hair growth. However, thisdocument does not in any way teach the use of this free-radicalprecursor for the light-protective, anti-ageing and/or anti-achetreatment of the skin.

SUMMARY OF THE INVENTION

The Applicant has found, surprisingly, that it is possible toincorporate into cosmetic and/or dermatological skin treatmentcompositions spin traps having light-protective, anti-ageing and/oranti-acne properties.

Another subject of the invention is a cosmetic or dermatologicalcomposition for topical treatment, characterized in that it comprises afirst dispersion of spherules which contain a spin trap used as anelectron paramagnetic resonance measurement probe, and a cosmetically ordermatologically acceptable medium. This composition may be appliedequally well to the human face and/or to the human body.

The composition of the invention advantageously contains a single spintrap, which facilitates its manufacture and lowers the manufacturingcost thereof compared with the compositions currently known for thelight-protective, anti-ageing and/or anti-acne treatment of the skin.This is possible because the spin traps used in the invention have theadvantage of being able to react with all the hydrophilic chemicalradical species of oxygen, such as O₂ •⁻⁻ and OH• and lipophilic radicalspecies as C₃ •, which are liable to form in the skin, whereas theactive agents conventionally used in the cosmetic field, such asanti-oxygen-free-radical agents (vitamin E andBHT--tert-butylhydroxytoleune--for example) are specific for the ROO•type of radical, which is formed subsequent to initiation of the damagecaused by the hydrophilic radical forms to the lipids of cutaneous cellmembranes. However, the species OH• is the species most reactive towardsbiomolecules.

Hitherto, no one had made the connection between spin-trapping andlight-protection, the combating of ageing and/or acne.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein: thesingle FIGURE attached represents curves showing the inhibition of theperoxidation of sebum (a lipidic liquid produced at the skin surface) bynitroxide radicals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Spin traps which may be used in the invention are especially nitroxideand nitrone radicals. In particular, these spin traps comprise one ormore rings, at least one of which contains a nitrogen atom bonded to theoxygen atom..

The spin traps of the composition of the invention are, for example,those cited in the document by L. B. Volodarsky "Advances in thechemistry of stable nitroxides", Janssen Chimica Acta, vol. 8,, No 3f p.12-19 (1990).

In particular, the spin trap of the invention as is chosen from the2,2,6,6-tetramethylpiperidine 1-oxide, 4-hydroxytetramethylpiperidine1-oxide, N-tert-butyl-alpha-phenylnitrone and doxylcyclohexane radicals,the salts ofN-(1-oxyl-2,2,6,6-tetramethyl-4-piperidyl)-N,N-dimethyl-N-hydroxyethylammonium,such as ASL (N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidyl)-N,N-dimethyl-N-hydroxyethylammonium iodide!, and mixtures thereof.

The spin traps of the invention can be prepared by conventional methodsknown to those of ordinary skill in the art.

The spin trap is advantageously present in an amount of from 0.001% to5% by weight relative to the total weight of the composition, betterstill in an amount of from 0.1% to 2% by weight.

According to the invention, the composition may be provided in the formof a gel, an emulsion, a serum or a lotion advantageously containingspherules which are preferably lipidic, or in the form of oil dropletsdispersed by lipid vesicles. The use of non-lipid spherules is, however,possible; in this case, polymeric nanoparticles such as nanospheres andnanocapsules may he used.

The terms "lipid spherules or vesicles" are intended to refer toparticles formed of a membrane consisting of one or more concentriclamellae, these lamellae containing one or more bimolecular layers ofamphiphilic lipids encapsulating an aqueous phase. The aqueous phase maycontain water-soluble active substances and the bimolecular layers ofamphiphilic lipids may contain lipophilic active substances. Thesespherules generally have a mean diameter of between 10 nm and 5,000 nm.

The lipid spherules used in the invention are, in particular, spherulescapable of releasing the spin trap into the deep layers of the skin,that is to say into the epidermis and the dermis. The reason for this isthat the sites in the skin which are the most sensitive to radicalspecies of oxygen are located in the epidermis and in the dermis. Inparticular, the radical species of oxygen cause considerable damageespecially in cell membranes (membrane permeability), cell nuclei(mutation by the action on RNA or DNA) and in tissues (necroses,degeneration) resulting in cutaneous ageing; these species react withthe various constituents of the skin.

Spherules capable of diffusing into the deep layers of the skin, alsoknown as spherules with deep-down action, are found in particular in thegelled state at room temperature (20° C.). In addition, these spheruleshave a diffusion constant for encapsulated ASL in the stratum corneum,which constitutes the surface layers of the skin, of >1×10⁻⁷ cm² s⁻¹.

Measurement of the diffusion constant D is carried out by combining twomethods using a paramagnetic probe, ASL: one-dimensional and periodicelectron paramagnetic resonance (EPR), on the one hand, and EPR kineticimaging, on the other hand. These two methods are respectively describedin the articles "Evaluation of liposomes as drug carriers into the skinby one-dimensional EPR imaging" by V. Gabrijelcic et al., InternationalJournal of Pharmaceutics, 62 (1990) p. 75-79, Elsevier, and "Liposomeentrapped molecules penetration into the skin measured by nitroxidereduction kinetic imaging" by V. Gabrijelcic et al., PeriodicumBiologorum vol. 93, No. 2, p. 245-246, (1991).

Moreover, these spherules with deep-down action have a strongencapsulating power.

Glucose is a labelling agent conventionally used for this type ofdetermination (cf. in particular Liposomes a practical approach by R. R.C. New, IRL Press (1990), p. 125-136). The degree of encapsulation isexpressed as the volume of glucose solution encapsulated in thespherules, measured in μl relative to the unit weight (mg) of the lipidsconstituting the membrane. This degree of encapsulation is determinedimmediately after the step of separation of the free glucose and of theencapsulated glucose (T₀), as well as twenty-four hours after thisseparation (T₂₄ hours).

The difference between these 2 successive determinations illustrates thepermeability of the spherules with respect to the encapsulated glucose.

The spherules (delivering the spin acceptor into the deep layers of theskin) have a high encapsulating power for the small water-solublemolecules which are conventionally modelled by glucose, thisencapsulating power being maintained for at least 24 hours.

The spherules with deep-down action may be formed of lipids comprisingat least one linear and saturated fatty chain having from 16 to 30carbon atoms, such as hydrogenated phospholipids (from plants or fromegg), saturated synthetic phospholipids such asdipalmitoylphosphatidylcholine, and polyol alkyl ethers or polyol alkylesters containing one, two or three fatty chains per molecule. Theselipids are used alone or as a mixture.

Another subject of the invention is a process for the topicalapplication of the composition defined above for the anti-ageing,anti-acne and/or light-protective treatment of the skin.

According to the invention, the spin traps have the characteristicfeature of reacting with chemical species of oxygen which have a veryshort lifetime and are thus highly reactive, that is to say withhydrophilic species of oxygen, which prevents, inter alia, the formationof ROO• radicals. They thus make it possible effectively to protectespecially the lipids, proteins and nucleic acids (RNA and DNA) of theskin.

It is advantageously possible to combine a sunscreen agent with the spintrap in order to prevent the formation of singlet oxygen in the skin,during the action of sunlight on the skin, and thus to enhance theeffectiveness of the composition of the invention in an anti-ageing,anti-acne and/or light-protective treatment of the skin. This screeningagent may consist in particular of an anti-UVA-radiation and/oranti-UVB-radiation screening agent of hydrophilic or lipophilic organicnature, such as benzene-1,4-di(3-methylidene-10-camphorsulphonic) acid,or of inorganic nature, such as nanopigments (TiO₂); it especiallyprovides protection for the surface of the skin, which is complementaryto the deep-down protection.

To do this, the screening agent is preferably encapsulated in spherules,especially lipid spherules, which are capable of diffusing into thesurface layers of the skin. These spherules, known as spherules actingat the surface, are in particular in the fluid state at room temperature(20° C.). Moreover, they provide a diffusion of ASL in the stratumcorneum with a diffusion coefficient D of <1×10⁻⁷ cm⁻² s⁻¹. In addition,they have a low encapsulating power. In other words, these spherulesretain the encapsulated glucose for less than 24 hours.

Moreover, the two types of spherules may contain other types of cosmeticactive agents, such as moisturizing agents (polyols and moreparticularly glycerine), keratolytic agents (5-n-octanoylsalicylicacid), anti-inflammatory agents, anti-microbial agents (triclosan),vitamins (A, C and F), proteins (amino acids, peptides and proteins),sugars (fructose), trace elements (Fe, Mg and Se), enzymes (lipases,proteases and DNA-repair enzymes), essential oils, etc.

The main lipids constituting the spherules which are active at thesurface are chosen in particular from the group comprising ionic lipids,especially such as natural plant- or egg-based phospholipids containingunsaturated fatty chains having from 16 to 30 carbon atoms; nonioniclipids such as polyol alkyl ethers or polyol alkyl esters comprising oneor more fatty chains per molecule, including at least one fatty chainwith a length of less than 16 carbon atoms, such as laurylpolyglycery-6-cetearyl glycol ether and mixtures thereof. The latterether is described in detail in Patent Application FR 92-09603 filed byL'Oreal.

It is possible, in a known manner, to incorporate into the lipid phaseconstituting the lipid membrane of the spherules, at least one additivechosen from the group formed of sterols (phytosterols, cholesterol orpolyoxyethylenated phytosterols), long-chain alcohols, diols and triols(phytanetriol), long-chain amines and the quaternary ammoniumderivatives thereof and/or an ionic additive chosen from the groupformed of phosphoric esters of fatty alcohols and the alkali metal (Naor K) salts thereof, such as dicetyl phosphate, sodium dicetylphosphate, alkyl sulphates (sodium cetyl sulphate), alkali metal saltsof cholesterol sulphate or of cholesterol phosphate, the sodium salt ofphosphatidic acid, and lipoamino acids and the salts thereof, such asthe sodium acylglutamates.

The composition of the invention may additionally contain all thecomponents conventionally used in the cosmetics field and in particulara vegetable oil, mineral oil, silicone-containing oil or synthetic oilwhich is dispersed in an aqueous phase, and also hydrophilic adjuvantssuch as gelling agents, preserving agents, opacifying agents, lipophilicadjuvants such as perfumes, pigments and fillers, as described in thedocuments FR-A-2,490,504 and FR-A-2,485,921. The dispersed oil mayrepresent from 2% to 40% by weight relative to the total weight of thecomposition and the adjuvants may represent from 0.1 to 10% by weight.

Examples of lipid vesicles (vesicles of the first category) deliveringthe spin trap into the deep layers of the skin which may be mentionedare vesicles obtained from the following lipids (CTFA name):

A/cholesterol/casein lipoamino acid, especially in 45/45/10 weight ratio(where A is a triglyceryl cetyl ether marketed by the company Chimexunder the name CHIMEXANE NL);

B/cholesterol/dicetyl phosphate, especially in a 60/35/5 weight ratio(where B is a mixture of triglyceryl mono-, di- and tricetyl ether,marketed by the company Chimex under the name CHIMEXANE NT);

Span 40 (from ICI, or sorbitan palmitate)/cholesterol/sodiumacylglutamate (marketed under the name HS11 by the company Ajinomoto),especially in a 47.5/47.5/5 weight ratio;

PEG 8 stearate/cholesterol/sodium acylglutamate, especially with a47.5/47.5/5 weight ratio (where PEG 8 stearate is polyethylene glycolcontaining 8 units of ethylene oxide, marketed by Unichema under thename PEG 400 stearate);

PEG 8 stearate/cholesterol/phytanEtriol/sodium acylglutamate, especiallywith a 47.5/20/27.5/5 weight ratio;

Hydrogenated lecithin/polyoxyethylenated phytosterol containing 5 unitsof ethylene oxide, especially in a 60/40 weight ratio;

Polyoxyethylenated methylglucose distearate containing 20 units ofethylene oxide/cholesterol/sodium acylglutamate, especially in a45/45/10 weight ratio (the distearate being, for example, that marketedunder the name GLUCAM E 20 distearate by Amerchol);

A/cholesterol/dicetyl phosphate, especially with a 47.5/47.5/5 weightratio (where A is a triglyceryl cetyl ether marketed by the companyChimex under the name CHIMEXANE NL);

Diglyceryl distearate (for example that marketed by Nihon under the nameEMALEX DS G2)/cholesterol/sodium acylglutamate, in a 45/45/10 weightratio;

Sucrose mono- and distearate (for example GRILLOTEN PSE 141 G fromGrillo)/cholesterol/sodium acylglutamate, especially in a 45/45/10weight ratio;

Tetraglyceryl tristearate (for example TETRAGLYN 3S fromNikkol)/cholesterol/sodium acylglutamate, especially in a 45/45/10weight ratio.

Examples of vesicles (of the second category) delivering an agent whichis active at the surface into the surface layers of the skin (forexample a screening agent or a moisturizing agent) which may bementioned are vesicles obtained from the following lipids:

Sunflower lecithin;

NATIPIDE II (soya lecithin/ethanol/water in a 60/20/20 weight ratio,marketed by Nattermann);

C (soya lecithin/cholesterol/propylene glycol in a 40/30/30 weightratio, marketed by Nattermann under the name NAT 50 PG);

D/dimyristyl phosphate, especially in a 95/5 weight ratio (where D is alauryl polyglyceryl-6-cetearyl glycol ether marketed by Chimaxunder thename CHIMRXANE NS).

Table I below gives, for some of the lipid vesicles obtained using theabove lipids, the diffusion constant D for ASL in the stratum cornsumand in the epidermis/dermis, as well as the degree of encapsulation ofglucose and the phase transition temperature of the main lipidconstituting the membrane. The diffusion constant was measured for anencapsulated ASL concentration of 0.35% by weight relative to the totalweight of the composition.

                                      TABLE I                                     __________________________________________________________________________                          Diffusion coefficient                                                                   Degree of                                                           D in 10.sup.-7 cm.sup.2 s.sup.-1                                                        encapsulation                                                                        Phase                                                Proportions                                                                           in the                                                                             in the                                                                             of glucose in                                                                        transition                                           % by weight                                                                           stratum                                                                            epidermis/                                                                         μl/mg                                                                             temperature                            Ref.                                                                             LIPID SYSTEMS                                                                            (mg)    corneum                                                                            dermis                                                                             T.sub.o                                                                          T.sub.24h                                                                         in °C.                          __________________________________________________________________________       1st type - deep down                                                       1  A/cholesterol/casein                                                                     45/45/10                                                                              42   5    7.5                                                                              6.8 50                                        lipoamino acid                                                                           (67.5/67.5/15)                                                  2  B/cholesterol/dicetyl                                                                    60/35/5 58   2    11.1                                                                             11.1                                                                              54                                        phosphate  (90/52.5/7.5)                                                   3  Span 40/cholesterol/                                                                     47.5/47.5/5                                                                           42   2    13.8                                                                             13.8                                                                              50                                        sodium acylglutamate                                                                     (71.25/71.25/7.5)                                               4  PEG 8 stearate/                                                                          47.5/47.5/5                                                                           42   2    14.4                                                                             14.4                                                                              55                                        cholesterol/sodium                                                                       (71.25/71.25/7.5)                                                  acylglutamate                                                              5  PEG 8 stearate/                                                                          47.5/20/27.5/5                                                                        8.3  2.5  4.1                                                                              3.0 55                                        cholesterol/phytanetriol/                                                                (71.25/30/                                                         sodium acylglutamate                                                                     41.25/7.5)                                                      6  Hydrogenated lecithin/                                                                   60/40   8    2    6.0                                                                              4.8 80                                        polyoxyethylenated                                                                       (90/60)                                                            phytosterol                                                                   2nd type - surface                                                         7  Sunflower lecithin                                                                       100     0.3  0.2  1.6                                                                              0   <0                                                   (150)                                                           8  Natipide II (soya                                                                        20/16/64                                                                              0.4  0.2  0.4                                                                              0   <0                                        lecithin/ethanol/water)                                                                  (30/24/96)                                                      9  C (soya lecithin/                                                                        60/20/20                                                                              0.25 0.1  1.8                                                                              0   <0                                        sterols/propylene glycol)                                                                (90/30/30)                                                      10 D/dimyristyl phosphate                                                                   95/5    0.3  0.2  2.0                                                                              0   14                                                   (142.5/7.5)                                                     __________________________________________________________________________

Measurement of the degree of encapsulation is carried out as describedin the RRC New document cited above, and that of the diffusion constantD is carried out as described above.

In order to recognize the state of the vesicles, the phase (fluid-gellamellar) transition temperature of the main lipid constituting themembrane thereof is determined by differential thermal analysis (DTA).

Another subject of the invention is a process for the light-protective,anti-ageing and/or anti-acne treatment of the skin, consisting inapplying to the skin the composition defined above.

Other characteristics and advantages of the invention will emerge moreclearly from the description which follows, which is given as anillustration and with no limitation being applied, in reference to thesingle FIGURE attached which represents curves showing the inhibition ofthe peroxidation of sebum (a lipidic liquid produced at the skinsurface) by nitroxide radicals. These tests were performed with simplecompositions containing from 0.05% to 1% by weight of nitroxide radicalsrelative to the weight of the composition, the remainder of thecomposition consisting of water. These tests were performed ex vivo,placing the various compositions in contact with sebum and thenirradiating them with UVA at a dose of 5 joules per cm² of sample.

The radicals tested are 2,2,6,6-tetramethylpiperidine 1-oxide (TPO),4-hydroxytetramethylpiperidine 1-oxide (HTPO),N-tertbutyl-alpha-phenylnitrone (TBP) and doxylcyclohexane (DHNO), andcorrespond respectively to the curves a, b, c and d of the FIGURE.

From these curves, a weak inhibition of the peroxidation of sebum isobserved in the concentration range between 0% and 0.1% with TPO, HTPOand TBP. This inhibition is close to that obtained with BHT at the sameconcentration. In the case of DHNO, an inhibition superior to that ofBHT is observed.

This inhibition becomes greater with 1% of active agent. It is at amaximum with DHNO and HTPO, 78% and 75% inhibition respectively asagainst 30% with TPO and 50% with TBP.

Consequently, these four radical nitroxides have a certain effectivenessagainst the peroxidation of sebum.

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the inventions and are not intended to be limitingthereof.

The total weight of vesicle contained in the composition is preferablyfrom 1 to 90 wt. %, more preferably from 5 to 70 wt. %, most preferablyfrom 5 to 20 wt. % based on the total weight of the composition.

The ratio of the amount of vesicles of the first dispersion type whichare capable of penetrating into the deep layers to the second dispersiontype which are capable of penetrating into the surface layers ispreferably from 1:9 to 9:1, more preferably from 3:7 to 7:3, mostpreferably from 4:6 to 6:4.

Within the context of the following examples the term qs 100 g is anamount needed to bring the total amount of the composition to 100 g.

The manufacture of compositions based on lipid vesicles acting at thesurface and lipid vesicles with deep-down action, in accordance with theinvention, using a nitroxide radical as active agent with deep-downaction, is described below.

A) Production of Lipid Vesicles Containing ASL

The constituent lipids of the wall of the vesicles are weighed out anddissolved in 10 ml of methanol. The alcoholic solution is thentransferred into a 50-ml roundflask with a ground joint, which issubsequently placed on a rotary evaporator such that the contents arethermostatted at a temperature of 30° C. The evaporation is continueduntil a dry film of lipid is deposited on the walls of the flask.

3 ml of an aqueous 0.01 molar solution of ASL are then added to theroundflask, which is subsequently shaken by hand for about 10 minutes,either at room temperature (20° C.) in the case of the vesicles of TableI of reference Nos. 7 to 10, or at a temperature of 50° C. in the caseof the vesicles of reference Nos. 1 to 6 of Table I. The medium is thenleft to equilibrate at room temperature for 2 hours, after which thedispersion is placed in a dialysis bag and in contact with 500 ml ofdistilled water. Dialysis takes place overnight. The next day, the wateris changed and the dialysis is continued for a further 4 hours.

A cotton thread 0.3 mm thick is then soaked in the vesicle dispersionand then placed in contact with a section of skin cut from a pig's earwhich has been freshly taken from an abattoir intended for food supply.

The ear sample taken is rinsed with water and cut into slices 1 mmthick, 5 mm wide and 10 mm long and then placed in a maintenance cell.Measurements of the diffusion of ASL in the skin are made in the 24hours following the taking of the skin sample.

B) Production of the Cosmetic Composition

1--Production of Vesicles of First Category (Diffusing Deep Down)

The vesicles (with deep-down action) are prepared according to a usualmethod for co-fusion of the various membrane constituents chosen (seeTable I). Thus, the membrane constituent having the lowest melting pointT_(m) is melted. The other membrane constituents are added and themixture is then homogenized with moderate stirring and is finallypartially hydrated, while maintaining the melting temperature T_(m)defined above.

An aqueous solution of a spin trap for the deep-down treatment is addedto the paste obtained. The mixture is stirred with a turbine for 1 h, 30min in order to hydrate fully, while maintaining the temperature T_(m).One or more other types of active agent for the deep-down treatment areoptionally added to the reaction medium (for example proteins, sugars,trace elements, essential oils), homogenization is carried out and thetemperature of the medium is lowered to room temperature (20° C.).

2--Production of Vesicles of the Second Category (Diffusing at theSurface)

An aqueous solution of a screening agent or several other active agents(for example polyols, amino acids, sugars, keratolytic agents, vitamins)for the surface treatment is introduced, at room temperature (20° C.)and with simple stirring, into the chosen mixture of constituents whichare to form the membrane of the vesicles acting at the surface (seeTable I). Vesicles acting at the surface encapsulating the screeningagent or any other active agent acting at the surface are thus obtained.

3--Production of the "Double-Liposome" Composition

The fatty phase (the oils) of the composition is added to the mediumcontaining the vesicles with deep-down action and it is dispersed (atroom temperature) with stirring. The reaction medium obtained is thenmixed with that containing the vesicles acting at the surface. Theadjuvants, such as preserving agents, a gelling agent which may beneutralized if necessary with a base (triethanolamine or sodiumhydroxide), and fragrances, etc., are then optionally added.

The product obtained is in the form of a soft and smooth white creamwhich may be used in the cosmetic and/or dermatological field forprotecting the skin against light radiation (visible and UV) and forcombating ageing of the skin and/or acne, at the surface and deep down.This cream may be used daily.

Specific examples of cosmetic compositions in accordance with theinvention are given below. The amounts are given as a percentage byweight.

EXAMPLE 1

Light-Protective Double-Liposome Cream

    ______________________________________                                        Liposomes with deep-down action:                                              Triglyceryl cetyl ether/cholesterol/dicetyl                                                          3.0%                                                   phosphate in a 47.5/47.5/5 weight                                             ratio                                                                         TPO (active agent)     1.0%                                                   Demineralized water    15.0%                                                  Liposomes acting at-the surface:                                              Soya lecithin          3.0%                                                   Benzene-1,4-di(3-methylidene-10-                                                                     0.5%                                                   camphorsulphonic) acid (screening                                             agent)                                                                        Triethanolamine (neutralizing agent)                                                                 0.3%                                                   Glycerine (active agent)                                                                             3.0%                                                   Demineralized water    15.0%                                                  Aqueous phase:                                                                Carboxyvinyl polymer (gelling agent)                                                                 0.4%                                                   Preserving agents      0.3%                                                   Triethanolamine        qs pH = 6                                              Demineralized water    qs 100%                                                Fatty phase:                                                                  Plant oils or mineral oils                                                                           10.0%                                                  Volatile silicone oil  5.0%                                                   ______________________________________                                    

EXAMPLE 2

Depigmenting Double-Liposome Cream

This cream differs from that of Example 1 in that TBP in used as activeagent with deep-down action, in place of TPO.

EXAMPLE 3

Anti-Ageing Double-Liposome Cream

    ______________________________________                                        Vesicles with deep-down action:                                               PEG 8 stearate/cholesterol/sodium acylglutamate                                                        5.0%                                                 in a 47.5/47.5/5 weight ratio                                                 HTPO (membrane active agent)                                                                           1.0%                                                 Demineralized water      15.0%                                                Fatty phase:                                                                  Plant oil                10.0%                                                Volatile silicone oil    5.0%                                                 Aqueous phase:                                                                Preserving agents        0.3%                                                 Glycerine (active agent) 3.0%                                                 Carboxyvinyl polymer (gelling agent)                                                                   0.4%                                                 Triethanolamine          qs pH = 6                                            Water                    qs 100%                                              ______________________________________                                    

EXAMPLE 4

Anti-Acne Double-Liposome Cream

    ______________________________________                                        Vesicles with deep-down action:                                               Sorbitan palmitate/cholesterol/sodium                                                                4.0%                                                   acylglutamate in a 47.5/47.5/5 weight                                         ratio                                                                         DHNO (water-soluble active agent)                                                                    0.2%                                                   Demineralized water    15.0                                                   Vesicles acting at the surface:                                               CHIMEXANE NS/dimyristyl phosphate in                                                                 3.0%                                                   a 95/5 weight ratio                                                           Octyl methoxycinnamate marketed under                                                                0.3%                                                   the name PARSOL MCX by the company                                            Givaudan                                                                      Glycerol (active agent)                                                                              3.0%                                                   Demineralized water    15.0%                                                  Fatty phase:                                                                  Plant oil              3.0%                                                   Volatile silicone oil  4.5%                                                   Aqueous phase:                                                                Triclosan              0.2%                                                   Preserving agents      0.3%                                                   Carboxyvinyl polymer (gelling agent)                                                                 0.9%                                                   Sodium hydroxide       qs pH = 6                                              Demineralized water    qs 100%                                                ______________________________________                                    

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

This application is based on French Patent Application 93/15869, filedwith the French Patent Office on Dec. 30, 1993, the entire contents ofwhich are hereby incorporated by reference.

What is claimed as new and desired to be secured by Letters Patent ofthe United States:
 1. A method for treating skin comprising applying tothe skin of a patient in need thereof, an effective amount of a cosmeticor dermatological composition comprising a spin trap, employed as anelectron paramagnetic resonance measurement probe, to affect thelight-protective, anti-ageing and/or anti-acne treatment of the skin,wherein said spin trap is present in an amount of from 0.001% to 5% byweight relative to the total weight of the composition.
 2. The method ofclaim 1, wherein said spin trap is selected from the group consisting ofa stable cyclic nitroxide comprising at least one ring containing anitrogen atom which is bonded to the oxygen atom and a stable nitroneradical comprising at least one ring containing a nitrogen atom which isbonded to the oxygen atom.
 3. The method of claim 2, wherein said spintrap comprises alkyl groups in n position α to said nitrogen atom. 4.The method of claim 2, wherein said spin trap is selected from the groupconsisting of 2,2,6,6-tetramethylpiperidine 1-oxide radical,4-hydroxytetramethylpiperidine 1-oxide radical,N-tertbutyl-α-phenylnitrone radical, doxylcyclohexane radical, andN-(1-oxyl-2,2,6,6-tetramethyl-4-piperidyl)-N,N-dimethyl-N-hydroxyethylammoniumsalts.
 5. The method of claim 2, wherein, said spin trap is in an amountof from 0.1% to 2% by weight relative to the total weight of thecomposition.
 6. The method of claim 2, wherein said spin trap isencapsulated in spherules.
 7. The method of claim 6, wherein saidspherules are lipid vesicles.
 8. The method of claim 6, wherein saidspherules comprise spherules with deep-down action which are capable ofdiffusing into the deep layers of the skin.
 9. The method of claim 8,wherein said spherules with deep-down action are in a gelled state atroom temperature.
 10. The method of claim 8, wherein said spherules withdeep-down action are formed of lipids comprising at least one linear andsaturated fatty chain having from 16 to 30 carbon atoms.
 11. The methodof claim 8, wherein said spherules with deep-down action are formed oflipids selected from the group consisting oftriglyceryl cetylother/cholesterol/casein lipoamino acid; a mixture of triglyceryl moro-,di- and tricetyl ether/cholesterol/dicetyl phosphate; triglyceryl cetylether/cholesterol/dicetyl phosphate; sorbitanpalmitate/cholesterol/sodium acylglutamate; PEG 8stearate/cholesterol/sodium acylglutamate; diglyceryldistearate/cholesterol/sodium acylglutamate; sucrose mono- anddistearate/cholesterol/sodium acylglutamate; PEG 8stearate/cholesterol/phytanetriol/sodium acylglutamate;polyoxyethylenated methylglucose distearate containing 20 mol ofethylene oxide/cholesterol/sodium acylglutamate; hydrogenatedlecithin/polyoxyethylenated phytosterol; and tetraglyceryltristearate/cholesterol/sodium acylglutamate.
 12. The method of claim 1,wherein said cosmetic or dermatological composition is provided in theform of a gel, an emulsion, a lotion, a serum or oil droplets dispersedby lipid vesicles.
 13. The method of claim 1, wherein said cosmetic ordermatological composition further comprises an oily phase which isdispersed in an aqueous phase.
 14. The method of claim 1, wherein saidcosmetic or dermatological composition further comprises hydrophilicadjuvants.
 15. The method of claim 1, wherein said cosmetic ordermatological composition further comprises a sunscreen, agent.
 16. Themethod of claim 15, wherein said sunscreen agent is encapsulated inspherules active at the surface which are capable of diffusing into thesurface layers of the skin.
 17. The method of claim 16, wherein saidvesicles active at the surface are formed of lipids selected from theconsisting of natural ionic phospholipids containing unsaturated fattychains having from 16 to 30 carbon atoms, polyol alkyl ethers or polyolalkyl esters having at least one fatty chain per molecule, including atleast one fatty chain with a length of less than 16 carbon atoms, andmixtures thereof.
 18. The method of claim 16, wherein said spherulesactive at the surface are formed of at least one lipid selected from thegroup Consisting of: Sunflower lecithin, Soya lecithin/ethanol/water,Soya lecithin/cholesterol/propylene glycol and Laurylpolyglyceryl-6-cetearyl glycol ether/dimyristyl phosphate.